Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Reexamination Certificate
1997-12-04
2001-08-07
Cuchlinski, Jr., William A. (Department: 3661)
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
C174S034000, C174S034000, C206S719000, C361S816000, C361S818000, C244S003140, C244S003160, C244S003190, C102S213000, C102S214000, C250S297000
Reexamination Certificate
active
06271464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to electrically conductive plastic housings, principally for optics, optical sensors, electronic printed wiring boards and, other systems and devices, the operation of which may be adversely affected by magnetic and/or radio frequency interference, for use in airborne detector systems and principally airborne missile guidance systems and the like.
2. Brief Description of the Prior Art
Guided airborne detector systems for dynamic airborne systems generally include, as a part of the airborne detector system, a detector guidance section for detecting target location and a control section for controlling airborne system trajectory in response to signals received from the detector guidance section in order to direct the airborne system to a selected target. Such detector and control systems must provide accurate and reliable outputs in order to insure that the desired trajectory is adhered to and that the ultimate target is reached. A problem with the detector and control electronics in such systems has been that magnetic and/or radio frequency interference emanating from the detector and/or the control section and/or other outside sources has been picked up by the airborne system electronics, thereby causing inaccurate readings to be provided, resulting in inaccurate trajectories with resultant failure to arrive at the desired target. For this reason, adequate shielding of the electrical components, cables and electrical interfaces between the detector, guidance and control sections of the airborne system has been critical to the accuracy and precision of the guidance which is required of the system.
In the prior art, this problem has been minimized by packaging and protecting electronic hardware and connections in the above described dynamic airborne systems using components fabricated from specially formed metallic housings, fastening hardware and interconnect components. The metallic forms were often expensive to produce, because their fabrication required close tolerances at joint and cable interface areas. Furthermore, if thin metallic components were damaged or joint areas were damaged prior to assembly, system protection against magnetic and/or radio frequency interference could be severely compromised. Though systems of the type described above have been used for many years and represent the prior state of the art, it is apparent that such systems have significant drawbacks including high cost and intricate assembly methods.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an assembly which minimizes the above noted problems of the prior art and which can be provided relatively inexpensively as compared with the above described prior art.
Briefly, there is provided an assembly including a two piece enclosure or housing of electrically conductive moldable plastic including a barrel portion and a bulkhead portion. Electrically conductive moldable plastic materials are well known and can be, for example, a moldable plastic material having electrically conductive fibers therein in sufficient quantity to provide electrical conductivity. The enclosure pieces lock together in an overlapping press fit by pushing the larger portion of the barrel into the bulkhead. The barrel contains a groove disposed adjacent the bulkhead portion which receives an electrically conductive o-ring to provide an electrically conductive path between the barrel and the bulkhead. This provides an electrically conductive shield for the electronic assembly which is disposed in the chamber formed by the bulkhead and the barrel.
The use of electrically conductive plastic parts, which cooperate to limit relative movement while providing adequate shielding, reduces part count, cost, weight and assembly time. The use of electrically conductive plastics also eliminates the need to machine to high tolerances metallic components, thereby reducing cost and the potential for defective parts. The assembly in accordance with the present invention shields the optical sensor and electrical components, and provides an adequate electrically conductive path for cable termination using the two piece electrically conductive plastic housing, the pieces of which is joined by an overlapped press fit. Cable termination is achieved using a simple threaded adapter which is fastened into the bulkhead portion, thereby creating an electrically conductive path between electrically conductive materials, such as, for example, electrically conductive fibers in the plastic and the metallic cable braid. Both the optical sensor and electrical components are mounted within the two piece housing during assembly.
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Baker & Botts L.L.P.
Cuchlinski Jr. William A.
Mancho Ronnie
Raytheon Company
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